The present invention relates to a data processing method and system for an input/output processing unit which executes retrieval processing, compare operations and set operations of a database management system (DBMS) at a high speed.
Conventionally, control unit and input/output unit such as a disk storage device are respectively assigned a unit address which is a unique identifier thereof. When a unit address is broadcasted together with an access request from a central processing unit, input/output unit, whose unit address is equal to the address, fetches the access request and performs processing. These unit addresses are assigned with hardware configuration definition for input/output units at system generation in a computer system.
For effectively utilizing information, the user requires that a database system provides better functions for (1) easy-learning, (2) use-friendly interface, or (3) high-performance.
A relational database (RDB) meets the above requirements (1) and (2) because of its simple table-type logical data structure.
Conventionally, database machines are often placed behind a host computer or a central processing unit so as to distribute loads of the central processing unit. However, such a structure causes heavy communication overhead between the database machine and the host computer. Also, the database machine has to provide a lot of complicated functions for database processing. A technique related to a CPU built-in type database processor for enhancing the processing speed of a relational database is proposed, for example, in "Nikkei Electronics", No. 414, pp. 185-206 (Feb. 9, 1987).
On the other hand, there has been proposed another configuration in which a data processing unit is disposed between a general-purpose host computer and a disk control unit. The data processing unit performs editing of pages (data) read out from a database efficiently. This data processing unit processes data-base access requirements for data stored in storage devices under the control unit. This configuration requires to define the data processing unit with hardware configuration definition and assign its unit address at system generation. Also, when a processing program in the host computer utilizes functions of the data processing unit, the processing program has to check the hardware configuration to confirm that a disk storage device to be accessed is connected to the data processing unit via disk control unit, and then issue access requests with the address of the data processing unit.